This is one of many Interoperability options.
This is similar but different than the Google Translate integration (which is a paid service)
You need to put two snippets of code in your site.
1- To prove that you control this site, add the meta google-translate-customization code (provided by Google) to tiki-admin.php?page=look -> Customization -> Custom HTML <head> Content
You need to tweak the code from Google slightly as explained here: